[PATCH 0/2] Update MAX31827 driver

[PATCH 0/2] Update MAX31827 driver

[Radu Sabau]

Add PEC support for MAX31827 by inspiring from lm90.c driver, hence
creating "pec" file and attaching it to the i2c device.

Add debugfs support for MAX31827 by creating max31827 directory in
/sys/kernel/debug/ folder that includes debugfs files specific
for configuration bits in the configuration register that one may
want to use in order to configure the chip in a specific way.

Radu Sabau (2):
  drivers: hwmon: max31827: Add PEC support
  drivers: hwmon: max31827: Add debugfs support

 Documentation/hwmon/max31827.rst |  38 +++-
 drivers/hwmon/max31827.c         | 297 +++++++++++++++++++++++++++++--
 2 files changed, 317 insertions(+), 18 deletions(-)

-- 
2.34.1

[PATCH 1/2] drivers: hwmon: max31827: Add PEC support

[Radu Sabau]

Add support for PEC by attaching PEC attribute to the i2c device.
Add pec_store and pec_show function for accesing the "pec" file.

Signed-off-by: Radu Sabau <radu.sabau@analog.com>
---
 Documentation/hwmon/max31827.rst | 13 ++++-
 drivers/hwmon/max31827.c         | 95 +++++++++++++++++++++++++++-----
 2 files changed, 92 insertions(+), 16 deletions(-)

diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
index 44ab9dc064cb..9c11a9518c67 100644
--- a/Documentation/hwmon/max31827.rst
+++ b/Documentation/hwmon/max31827.rst
@@ -131,7 +131,14 @@ The Fault Queue bits select how many consecutive temperature faults must occur
 before overtemperature or undertemperature faults are indicated in the
 corresponding status bits.
 
-Notes
------
+PEC Support
+-----------
+
+When reading a register value, the PEC byte is computed and sent by the chip.
+
+PEC on word data transaction respresents a signifcant increase in bandwitdh
+usage (+33% for both write and reads) in normal conditions.
 
-PEC is not implemented.
+Since this operation implies there will be an extra delay to each
+transaction, PEC can be disabled or enabled through sysfs.
+Just write 1  to the "pec" file for enabling PEC and 0 for disabling it.
diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c
index f8a13b30f100..16a1524413db 100644
--- a/drivers/hwmon/max31827.c
+++ b/drivers/hwmon/max31827.c
@@ -11,19 +11,20 @@
 #include <linux/hwmon.h>
 #include <linux/i2c.h>
 #include <linux/mutex.h>
-#include <linux/of_device.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/of_device.h>
 
-#define MAX31827_T_REG			0x0
+#define MAX31827_T_REG	0x0
 #define MAX31827_CONFIGURATION_REG	0x2
-#define MAX31827_TH_REG			0x4
-#define MAX31827_TL_REG			0x6
-#define MAX31827_TH_HYST_REG		0x8
-#define MAX31827_TL_HYST_REG		0xA
+#define MAX31827_TH_REG	0x4
+#define MAX31827_TL_REG 0x6
+#define MAX31827_TH_HYST_REG	0x8
+#define MAX31827_TL_HYST_REG	0xA
 
 #define MAX31827_CONFIGURATION_1SHOT_MASK	BIT(0)
 #define MAX31827_CONFIGURATION_CNV_RATE_MASK	GENMASK(3, 1)
+#define MAX31827_CONFIGURATION_PEC_EN_MASK	BIT(4)
 #define MAX31827_CONFIGURATION_TIMEOUT_MASK	BIT(5)
 #define MAX31827_CONFIGURATION_RESOLUTION_MASK	GENMASK(7, 6)
 #define MAX31827_CONFIGURATION_ALRM_POL_MASK	BIT(8)
@@ -46,6 +47,8 @@
 #define MAX31827_M_DGR_TO_16_BIT(x)	(((x) << 4) / 1000)
 #define MAX31827_DEVICE_ENABLE(x)	((x) ? 0xA : 0x0)
 
+#define DEBUG_FS_DATA_MAX	16
+
 enum chips { max31827 = 1, max31828, max31829 };
 
 enum max31827_cnv {
@@ -151,8 +154,8 @@ static int shutdown_write(struct max31827_state *st, unsigned int reg,
 		goto unlock;
 
 	ret = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
-				 MAX31827_CONFIGURATION_CNV_RATE_MASK,
-				 cnv_rate);
+				   MAX31827_CONFIGURATION_CNV_RATE_MASK,
+				   cnv_rate);
 
 unlock:
 	mutex_unlock(&st->lock);
@@ -344,7 +347,7 @@ static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
 		switch (attr) {
 		case hwmon_temp_enable:
 			if (val >> 1)
-				return -EINVAL;
+				return -EOPNOTSUPP;
 
 			mutex_lock(&st->lock);
 			/**
@@ -384,7 +387,7 @@ static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
 	case hwmon_chip:
 		if (attr == hwmon_chip_update_interval) {
 			if (!st->enable)
-				return -EINVAL;
+				return -EOPNOTSUPP;
 
 			/*
 			 * Convert the desired conversion rate into register
@@ -472,11 +475,60 @@ static ssize_t temp1_resolution_store(struct device *dev,
 
 	return ret ? ret : count;
 }
-
 static DEVICE_ATTR_RW(temp1_resolution);
 
+static ssize_t pec_show(struct device *dev, struct device_attribute *devattr,
+			char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", !!(client->flags & I2C_CLIENT_PEC));
+}
+
+static ssize_t pec_store(struct device *dev, struct device_attribute *devattr,
+			 const char *buf, size_t count)
+{
+	struct max31827_state *st = dev_get_drvdata(dev);
+	struct i2c_client *client = to_i2c_client(dev);
+	unsigned int val, val2;
+	int err;
+
+	err = kstrtouint(buf, 10, &val);
+	if (err < 0)
+		return err;
+
+	val2 = FIELD_PREP(MAX31827_CONFIGURATION_PEC_EN_MASK, !!val);
+
+	switch (val) {
+	case 0:
+		err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
+					 MAX31827_CONFIGURATION_PEC_EN_MASK,
+					 val2);
+		if (err)
+			return err;
+
+		client->flags &= ~I2C_CLIENT_PEC;
+		break;
+	case 1:
+		err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
+					 MAX31827_CONFIGURATION_PEC_EN_MASK,
+					 val2);
+		if (err)
+			return err;
+
+		client->flags |= I2C_CLIENT_PEC;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return count;
+}
+static DEVICE_ATTR_RW(pec);
+
 static struct attribute *max31827_attrs[] = {
 	&dev_attr_temp1_resolution.attr,
+	&dev_attr_pec.attr,
 	NULL
 };
 ATTRIBUTE_GROUPS(max31827);
@@ -493,8 +545,8 @@ static int max31827_init_client(struct max31827_state *st,
 				struct device *dev)
 {
 	struct fwnode_handle *fwnode;
+	unsigned int data, lsb_idx;
 	unsigned int res = 0;
-	u32 data, lsb_idx;
 	enum chips type;
 	bool prop;
 	int ret;
@@ -578,6 +630,11 @@ static int max31827_init_client(struct max31827_state *st,
 	return regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, res);
 }
 
+static void max31827_remove_pec(void *dev)
+{
+	device_remove_file(dev, &dev_attr_pec);
+}
+
 static const struct hwmon_channel_info *max31827_info[] = {
 	HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT | HWMON_T_MIN |
 					 HWMON_T_MIN_HYST | HWMON_T_MIN_ALARM |
@@ -627,6 +684,16 @@ static int max31827_probe(struct i2c_client *client)
 	if (err)
 		return err;
 
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC)) {
+		err = device_create_file(dev, &dev_attr_pec);
+		if (err)
+			return err;
+
+		err = devm_add_action_or_reset(dev, max31827_remove_pec, dev);
+		if (err)
+			return err;
+	}
+
 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st,
 							 &max31827_chip_info,
 							 max31827_groups);
@@ -652,15 +719,17 @@ static const struct of_device_id max31827_of_match[] = {
 MODULE_DEVICE_TABLE(of, max31827_of_match);
 
 static struct i2c_driver max31827_driver = {
+	.class = I2C_CLASS_HWMON,
 	.driver = {
 		.name = "max31827",
 		.of_match_table = max31827_of_match,
 	},
-	.probe = max31827_probe,
+	.probe_new = max31827_probe,
 	.id_table = max31827_i2c_ids,
 };
 module_i2c_driver(max31827_driver);
 
 MODULE_AUTHOR("Daniel Matyas <daniel.matyas@analog.com>");
+MODULE_AUTHOR("Radu Sabau <radu.sabau@analog.com>");
 MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver");
 MODULE_LICENSE("GPL");
-- 
2.34.1

Re: [PATCH 1/2] drivers: hwmon: max31827: Add PEC support

[Nuno Sá]

On Wed, 2024-05-22 at 15:39 +0300, Radu Sabau wrote:
> Add support for PEC by attaching PEC attribute to the i2c device.
> Add pec_store and pec_show function for accesing the "pec" file.
> 
> Signed-off-by: Radu Sabau <radu.sabau@analog.com>
> ---
>  Documentation/hwmon/max31827.rst | 13 ++++-
>  drivers/hwmon/max31827.c         | 95 +++++++++++++++++++++++++++-----
>  2 files changed, 92 insertions(+), 16 deletions(-)
> 
> diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
> index 44ab9dc064cb..9c11a9518c67 100644
> --- a/Documentation/hwmon/max31827.rst
> +++ b/Documentation/hwmon/max31827.rst
> @@ -131,7 +131,14 @@ The Fault Queue bits select how many consecutive temperature
> faults must occur
>  before overtemperature or undertemperature faults are indicated in the
>  corresponding status bits.
>  
> -Notes
> ------
> +PEC Support
> +-----------
> +
> +When reading a register value, the PEC byte is computed and sent by the chip.
> +
> +PEC on word data transaction respresents a signifcant increase in bandwitdh
> +usage (+33% for both write and reads) in normal conditions.
>  
> -PEC is not implemented.
> +Since this operation implies there will be an extra delay to each
> +transaction, PEC can be disabled or enabled through sysfs.
> +Just write 1  to the "pec" file for enabling PEC and 0 for disabling it.
> diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c
> index f8a13b30f100..16a1524413db 100644
> --- a/drivers/hwmon/max31827.c
> +++ b/drivers/hwmon/max31827.c
> @@ -11,19 +11,20 @@
>  #include <linux/hwmon.h>
>  #include <linux/i2c.h>
>  #include <linux/mutex.h>
> -#include <linux/of_device.h>
>  #include <linux/regmap.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/of_device.h>
>  

Looks like unrelated change...
> -#define MAX31827_T_REG			0x0
> +#define MAX31827_T_REG	0x0
>  #define MAX31827_CONFIGURATION_REG	0x2
> -#define MAX31827_TH_REG			0x4
> -#define MAX31827_TL_REG			0x6
> -#define MAX31827_TH_HYST_REG		0x8
> -#define MAX31827_TL_HYST_REG		0xA
> +#define MAX31827_TH_REG	0x4
> +#define MAX31827_TL_REG 0x6
> +#define MAX31827_TH_HYST_REG	0x8
> +#define MAX31827_TL_HYST_REG	0xA

ditto for all the other places

...

>  
> +static ssize_t pec_show(struct device *dev, struct device_attribute *devattr,
> +			char *buf)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", !!(client->flags &
> I2C_CLIENT_PEC));

sysfs_emit()

> +}
> +
> +static ssize_t pec_store(struct device *dev, struct device_attribute *devattr,
> +			 const char *buf, size_t count)
> +{
> +	struct max31827_state *st = dev_get_drvdata(dev);
> +	struct i2c_client *client = to_i2c_client(dev);
> +	unsigned int val, val2;
> +	int err;
> +
> +	err = kstrtouint(buf, 10, &val);
> +	if (err < 0)
> +		return err;
> +
> +	val2 = FIELD_PREP(MAX31827_CONFIGURATION_PEC_EN_MASK, !!val);
> +

Why not just val?

> +	switch (val) {
> +	case 0:
> +		err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
> +					 MAX31827_CONFIGURATION_PEC_EN_MASK,
> +					 val2);
> +		if (err)
> +			return err;
> +
> +		client->flags &= ~I2C_CLIENT_PEC;
> +		break;
> +	case 1:
> +		err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
> +					 MAX31827_CONFIGURATION_PEC_EN_MASK,
> +					 val2);
> +		if (err)
> +			return err;
> +
> +		client->flags |= I2C_CLIENT_PEC;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return count;
> +}
> +static DEVICE_ATTR_RW(pec);
> +
>  static struct attribute *max31827_attrs[] = {
>  	&dev_attr_temp1_resolution.attr,
> +	&dev_attr_pec.attr,

Do we need it in here??


- Nuno Sá

Re: [PATCH 1/2] drivers: hwmon: max31827: Add PEC support

[kernel test robot]

Hi Radu,

kernel test robot noticed the following build errors:

[auto build test ERROR on groeck-staging/hwmon-next]
[also build test ERROR on linus/master v6.9 next-20240523]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Radu-Sabau/drivers-hwmon-max31827-Add-PEC-support/20240523-004248
base:   https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git hwmon-next
patch link:    https://lore.kernel.org/r/20240522123923.22320-2-radu.sabau%40analog.com
patch subject: [PATCH 1/2] drivers: hwmon: max31827: Add PEC support
config: i386-buildonly-randconfig-003-20240523 (https://download.01.org/0day-ci/archive/20240523/202405231257.IOuSANzt-lkp@intel.com/config)
compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240523/202405231257.IOuSANzt-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405231257.IOuSANzt-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/hwmon/max31827.c:727:3: error: field designator 'probe_new' does not refer to any field in type 'struct i2c_driver'
     727 |         .probe_new = max31827_probe,
         |         ~^~~~~~~~~~~~~~~~~~~~~~~~~~
   1 error generated.


vim +727 drivers/hwmon/max31827.c

   720	
   721	static struct i2c_driver max31827_driver = {
   722		.class = I2C_CLASS_HWMON,
   723		.driver = {
   724			.name = "max31827",
   725			.of_match_table = max31827_of_match,
   726		},
 > 727		.probe_new = max31827_probe,
   728		.id_table = max31827_i2c_ids,
   729	};
   730	module_i2c_driver(max31827_driver);
   731	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 1/2] drivers: hwmon: max31827: Add PEC support

[Guenter Roeck]

On 5/22/24 05:39, Radu Sabau wrote:
> Add support for PEC by attaching PEC attribute to the i2c device.
> Add pec_store and pec_show function for accesing the "pec" file.
> 
accessing

> Signed-off-by: Radu Sabau <radu.sabau@analog.com>
> ---

There are lots of unrelated changes. Please drop all those, or
if they are supposed to fix checkpatch problems submit as separate
patches. I will not accept coding style changes unless they fix
checkpatch problems.

The patch is not based on the latest kernel. Please rebase
at least on top of v6.9.

More comments inline.

>   Documentation/hwmon/max31827.rst | 13 ++++-
>   drivers/hwmon/max31827.c         | 95 +++++++++++++++++++++++++++-----
>   2 files changed, 92 insertions(+), 16 deletions(-)
> 
> diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
> index 44ab9dc064cb..9c11a9518c67 100644
> --- a/Documentation/hwmon/max31827.rst
> +++ b/Documentation/hwmon/max31827.rst
> @@ -131,7 +131,14 @@ The Fault Queue bits select how many consecutive temperature faults must occur
>   before overtemperature or undertemperature faults are indicated in the
>   corresponding status bits.
>   
> -Notes
> ------
> +PEC Support
> +-----------
> +
> +When reading a register value, the PEC byte is computed and sent by the chip.
> +
> +PEC on word data transaction respresents a signifcant increase in bandwitdh
> +usage (+33% for both write and reads) in normal conditions.
>   
> -PEC is not implemented.
> +Since this operation implies there will be an extra delay to each
> +transaction, PEC can be disabled or enabled through sysfs.
> +Just write 1  to the "pec" file for enabling PEC and 0 for disabling it.
> diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c
> index f8a13b30f100..16a1524413db 100644
> --- a/drivers/hwmon/max31827.c
> +++ b/drivers/hwmon/max31827.c
> @@ -11,19 +11,20 @@
>   #include <linux/hwmon.h>
>   #include <linux/i2c.h>
>   #include <linux/mutex.h>
> -#include <linux/of_device.h>
>   #include <linux/regmap.h>
>   #include <linux/regulator/consumer.h>
> +#include <linux/of_device.h>
>   

Include files should be in alphabetic order. The above change
deserves a NACK.

> -#define MAX31827_T_REG			0x0
> +#define MAX31827_T_REG	0x0
>   #define MAX31827_CONFIGURATION_REG	0x2
> -#define MAX31827_TH_REG			0x4
> -#define MAX31827_TL_REG			0x6
> -#define MAX31827_TH_HYST_REG		0x8
> -#define MAX31827_TL_HYST_REG		0xA
> +#define MAX31827_TH_REG	0x4
> +#define MAX31827_TL_REG 0x6
> +#define MAX31827_TH_HYST_REG	0x8
> +#define MAX31827_TL_HYST_REG	0xA
>   
>   #define MAX31827_CONFIGURATION_1SHOT_MASK	BIT(0)
>   #define MAX31827_CONFIGURATION_CNV_RATE_MASK	GENMASK(3, 1)
> +#define MAX31827_CONFIGURATION_PEC_EN_MASK	BIT(4)
>   #define MAX31827_CONFIGURATION_TIMEOUT_MASK	BIT(5)
>   #define MAX31827_CONFIGURATION_RESOLUTION_MASK	GENMASK(7, 6)
>   #define MAX31827_CONFIGURATION_ALRM_POL_MASK	BIT(8)
> @@ -46,6 +47,8 @@
>   #define MAX31827_M_DGR_TO_16_BIT(x)	(((x) << 4) / 1000)
>   #define MAX31827_DEVICE_ENABLE(x)	((x) ? 0xA : 0x0)
>   
> +#define DEBUG_FS_DATA_MAX	16
> +
>   enum chips { max31827 = 1, max31828, max31829 };
>   
>   enum max31827_cnv {
> @@ -151,8 +154,8 @@ static int shutdown_write(struct max31827_state *st, unsigned int reg,
>   		goto unlock;
>   
>   	ret = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
> -				 MAX31827_CONFIGURATION_CNV_RATE_MASK,
> -				 cnv_rate);
> +				   MAX31827_CONFIGURATION_CNV_RATE_MASK,
> +				   cnv_rate);
>   
>   unlock:
>   	mutex_unlock(&st->lock);
> @@ -344,7 +347,7 @@ static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
>   		switch (attr) {
>   		case hwmon_temp_enable:
>   			if (val >> 1)
> -				return -EINVAL;
> +				return -EOPNOTSUPP;

Why ?

>   
>   			mutex_lock(&st->lock);
>   			/**
> @@ -384,7 +387,7 @@ static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
>   	case hwmon_chip:
>   		if (attr == hwmon_chip_update_interval) {
>   			if (!st->enable)
> -				return -EINVAL;
> +				return -EOPNOTSUPP;
>   
>   			/*
>   			 * Convert the desired conversion rate into register
> @@ -472,11 +475,60 @@ static ssize_t temp1_resolution_store(struct device *dev,
>   
>   	return ret ? ret : count;
>   }
> -
>   static DEVICE_ATTR_RW(temp1_resolution);
>   
> +static ssize_t pec_show(struct device *dev, struct device_attribute *devattr,
> +			char *buf)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%d\n", !!(client->flags & I2C_CLIENT_PEC));
> +}
> +
> +static ssize_t pec_store(struct device *dev, struct device_attribute *devattr,
> +			 const char *buf, size_t count)
> +{
> +	struct max31827_state *st = dev_get_drvdata(dev);
> +	struct i2c_client *client = to_i2c_client(dev);
> +	unsigned int val, val2;
> +	int err;
> +
> +	err = kstrtouint(buf, 10, &val);
> +	if (err < 0)
> +		return err;
> +
> +	val2 = FIELD_PREP(MAX31827_CONFIGURATION_PEC_EN_MASK, !!val);

This is completely unnecessary.

> +
> +	switch (val) {
> +	case 0:
> +		err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
> +					 MAX31827_CONFIGURATION_PEC_EN_MASK,
> +					 val2);

	s/val2/0/

> +		if (err)
> +			return err;
> +
> +		client->flags &= ~I2C_CLIENT_PEC;
> +		break;
> +	case 1:
> +		err = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
> +					 MAX31827_CONFIGURATION_PEC_EN_MASK,
> +					 val2);

	s/val2/MAX31827_CONFIGURATION_PEC_EN_MASK/

> +		if (err)
> +			return err;
> +
> +		client->flags |= I2C_CLIENT_PEC;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return count;
> +}
> +static DEVICE_ATTR_RW(pec);
> +
>   static struct attribute *max31827_attrs[] = {
>   	&dev_attr_temp1_resolution.attr,
> +	&dev_attr_pec.attr,

Attach to i2c interface.

Oh, wait, you are doing that as well. So there would be two
"pec" attribute files, one attached to the i2c interface
and one attached to the hwmon interface. Care to explain ?

>   	NULL
>   };
>   ATTRIBUTE_GROUPS(max31827);
> @@ -493,8 +545,8 @@ static int max31827_init_client(struct max31827_state *st,
>   				struct device *dev)
>   {
>   	struct fwnode_handle *fwnode;
> +	unsigned int data, lsb_idx;
>   	unsigned int res = 0;
> -	u32 data, lsb_idx;

I am quite completely at loss trying to understand why you are making those changes.

>   	enum chips type;
>   	bool prop;
>   	int ret;
> @@ -578,6 +630,11 @@ static int max31827_init_client(struct max31827_state *st,
>   	return regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, res);
>   }
>   
> +static void max31827_remove_pec(void *dev)
> +{
> +	device_remove_file(dev, &dev_attr_pec);
> +}
> +
>   static const struct hwmon_channel_info *max31827_info[] = {
>   	HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT | HWMON_T_MIN |
>   					 HWMON_T_MIN_HYST | HWMON_T_MIN_ALARM |
> @@ -627,6 +684,16 @@ static int max31827_probe(struct i2c_client *client)
>   	if (err)
>   		return err;
>   
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC)) {

This does not make sense. If the controller does not support PEC,
it does not make sense to provide an attribute to enable it.

> +		err = device_create_file(dev, &dev_attr_pec);
> +		if (err)
> +			return err;
> +
> +		err = devm_add_action_or_reset(dev, max31827_remove_pec, dev);
> +		if (err)
> +			return err;
> +	}
> +
>   	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st,
>   							 &max31827_chip_info,
>   							 max31827_groups);
> @@ -652,15 +719,17 @@ static const struct of_device_id max31827_of_match[] = {
>   MODULE_DEVICE_TABLE(of, max31827_of_match);
>   
>   static struct i2c_driver max31827_driver = {
> +	.class = I2C_CLASS_HWMON,
>   	.driver = {
>   		.name = "max31827",
>   		.of_match_table = max31827_of_match,
>   	},
> -	.probe = max31827_probe,
> +	.probe_new = max31827_probe,
>   	.id_table = max31827_i2c_ids,
>   };
>   module_i2c_driver(max31827_driver);
>   
>   MODULE_AUTHOR("Daniel Matyas <daniel.matyas@analog.com>");
> +MODULE_AUTHOR("Radu Sabau <radu.sabau@analog.com>");

Providing a patch to a driver does not make you the author.

>   MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver");
>   MODULE_LICENSE("GPL");

[PATCH 2/2] drivers: hwmon: max31827: Add debugfs support

[Radu Sabau]

Add debugfs support by creating directory in sys-fs which includes
debugfs specific files used for configuring the device by
preference.

Signed-off-b: Radu Sabau <radu.sabau@analog.com>
---
 Documentation/hwmon/max31827.rst |  25 ++++
 drivers/hwmon/max31827.c         | 202 ++++++++++++++++++++++++++++++-
 2 files changed, 225 insertions(+), 2 deletions(-)

diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
index 9c11a9518c67..940310be6075 100644
--- a/Documentation/hwmon/max31827.rst
+++ b/Documentation/hwmon/max31827.rst
@@ -142,3 +142,28 @@ usage (+33% for both write and reads) in normal conditions.
 Since this operation implies there will be an extra delay to each
 transaction, PEC can be disabled or enabled through sysfs.
 Just write 1  to the "pec" file for enabling PEC and 0 for disabling it.
+
+DebugFs entries
+---------------
+
+The chip also has a configuration register where each bit stands for a specific
+functionality to be configured. Hence as one would like to have access to these
+features, we give access to them in debugfs.
+
+.. warning:: The debugfs interface is subject to change without notice
+             and is only available when the kernel is compiled with
+             ``CONFIG_DEBUG_FS`` defined.
+
+``/sys/kernel/debug/max31827/``
+contains the following attributes:
+
+==============  ===============================================================
+alarm_polarity  Write 1 for ALARM pin active state is low, 0 otherwise
+comp_int        Set to 1 if OT and UT status bits are in interrupt mode
+fault_queue     Number of consecutive temperature faults until OT and UT faults
+                are indicated in status bits
+pec_error       Set to 1 if PEC Enable bit is set, 0 otherwise
+resolution      2-bit value that select the conversion resolution, please see
+                datasheet for corresponding values
+timeout         Write 1 do disable bus timeout, 0 otherwise
+==============  ===============================================================
diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c
index 16a1524413db..1303ea81250d 100644
--- a/drivers/hwmon/max31827.c
+++ b/drivers/hwmon/max31827.c
@@ -13,8 +13,19 @@
 #include <linux/mutex.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/debugfs.h>
 #include <linux/of_device.h>
 
+enum {
+	MAX31827_DEBUGFS_TIMEOUT = 0,
+	MAX31827_DEBUGFS_RESOLUTION,
+	MAX31827_DEBUGFS_ALARM_POLARITY,
+	MAX31827_DEBUGFS_COMP_INT,
+	MAX31827_DEBUGFS_FAULT_QUEUE,
+	MAX31827_DEBUGFS_PEC_ERROR,
+	MAX31827_DEBUGFS_NUM_ENTRIES
+};
+
 #define MAX31827_T_REG	0x0
 #define MAX31827_CONFIGURATION_REG	0x2
 #define MAX31827_TH_REG	0x4
@@ -30,6 +41,7 @@
 #define MAX31827_CONFIGURATION_ALRM_POL_MASK	BIT(8)
 #define MAX31827_CONFIGURATION_COMP_INT_MASK	BIT(9)
 #define MAX31827_CONFIGURATION_FLT_Q_MASK	GENMASK(11, 10)
+#define MAX31827_CONFIGURATION_PEC_ERR_MASK	BIT(13)
 #define MAX31827_CONFIGURATION_U_TEMP_STAT_MASK	BIT(14)
 #define MAX31827_CONFIGURATION_O_TEMP_STAT_MASK	BIT(15)
 
@@ -92,12 +104,17 @@ static const u16 max31827_conv_times[] = {
 	[MAX31827_RES_12_BIT] = MAX31827_12_BIT_CNV_TIME,
 };
 
+struct max31827_debugfs_data {
+	int debugfs_entries[MAX31827_DEBUGFS_NUM_ENTRIES];
+};
+
 struct max31827_state {
 	/*
 	 * Prevent simultaneous access to the i2c client.
 	 */
 	struct mutex lock;
 	struct regmap *regmap;
+	struct max31827_debugfs_data psu;
 	bool enable;
 	unsigned int resolution;
 	unsigned int update_interval;
@@ -552,7 +569,6 @@ static int max31827_init_client(struct max31827_state *st,
 	int ret;
 
 	fwnode = dev_fwnode(dev);
-
 	st->enable = true;
 	res |= MAX31827_DEVICE_ENABLE(1);
 
@@ -655,6 +671,182 @@ static const struct hwmon_chip_info max31827_chip_info = {
 	.info = max31827_info,
 };
 
+#ifdef CONFIG_DEBUG_FS
+static ssize_t max31827_debugfs_read(struct file *file, char __user *buf,
+				     size_t count, loff_t *ppos)
+{
+	char tbuf[DEBUG_FS_DATA_MAX] = { 0 };
+	struct max31827_debugfs_data *psu;
+	struct max31827_state *st;
+	int *attrp = file_inode(file)->i_private;
+	int attr = *attrp;
+	unsigned int uval;
+	int ret, len;
+
+	psu = container_of(attrp, struct max31827_debugfs_data, debugfs_entries[attr]);
+	st = container_of(psu, struct max31827_state, psu);
+
+	ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &uval);
+	if (ret)
+		return ret;
+
+	switch (attr) {
+	case MAX31827_DEBUGFS_TIMEOUT:
+		uval = FIELD_GET(MAX31827_CONFIGURATION_TIMEOUT_MASK, uval);
+		len = scnprintf(tbuf, DEBUG_FS_DATA_MAX, "%d\n", uval);
+		break;
+	case MAX31827_DEBUGFS_RESOLUTION:
+		uval = FIELD_GET(MAX31827_CONFIGURATION_RESOLUTION_MASK, uval);
+		len = scnprintf(tbuf, DEBUG_FS_DATA_MAX, "%d\n", uval);
+		break;
+	case MAX31827_DEBUGFS_ALARM_POLARITY:
+		uval = FIELD_GET(MAX31827_CONFIGURATION_ALRM_POL_MASK, uval);
+		len = scnprintf(tbuf, DEBUG_FS_DATA_MAX, "%d\n", uval);
+		break;
+	case MAX31827_DEBUGFS_COMP_INT:
+		uval = FIELD_GET(MAX31827_CONFIGURATION_COMP_INT_MASK, uval);
+		len = scnprintf(tbuf, DEBUG_FS_DATA_MAX, "%d\n", uval);
+		break;
+	case MAX31827_DEBUGFS_FAULT_QUEUE:
+		uval = FIELD_GET(MAX31827_CONFIGURATION_FLT_Q_MASK, uval);
+		len = scnprintf(tbuf, DEBUG_FS_DATA_MAX, "%d\n", uval);
+		break;
+	case MAX31827_DEBUGFS_PEC_ERROR:
+		uval = FIELD_GET(MAX31827_CONFIGURATION_PEC_ERR_MASK, uval);
+		len = scnprintf(tbuf, DEBUG_FS_DATA_MAX, "%d\n", uval);
+		break;
+	default:
+		len = strscpy(tbuf, "Invalid\n", DEBUG_FS_DATA_MAX);
+	}
+
+	return simple_read_from_buffer(buf, count, ppos, tbuf, len);
+}
+
+static ssize_t max31827_debugfs_write(struct file *file, const char __user *buf,
+				      size_t count, loff_t *ppos)
+{
+	char tbuf[DEBUG_FS_DATA_MAX] = { 0 };
+	struct max31827_debugfs_data *psu;
+	struct max31827_state *st;
+	int *attrp = file_inode(file)->i_private;
+	int attr = *attrp;
+	u16 uval;
+	int ret;
+
+	pr_info("attr = %d\n", attr);
+	psu = container_of(attrp, struct max31827_debugfs_data, debugfs_entries[attr]);
+	pr_info("First container ok.\n");
+	st = container_of(psu, struct max31827_state, psu);
+
+	ret = kstrtou16_from_user(buf, count, 0, &uval);
+	if (ret)
+		return ret;
+
+	pr_info("uval = %s\n", tbuf);
+
+	switch (attr) {
+	case MAX31827_DEBUGFS_TIMEOUT:
+		uval = FIELD_PREP(MAX31827_CONFIGURATION_TIMEOUT_MASK, uval);
+		ret = regmap_update_bits(st->regmap,
+					 MAX31827_CONFIGURATION_REG,
+					 MAX31827_CONFIGURATION_TIMEOUT_MASK,
+					 uval);
+		break;
+	case MAX31827_DEBUGFS_RESOLUTION:
+		uval = FIELD_PREP(MAX31827_CONFIGURATION_RESOLUTION_MASK, uval);
+		ret = regmap_update_bits(st->regmap,
+					 MAX31827_CONFIGURATION_REG,
+					 MAX31827_CONFIGURATION_RESOLUTION_MASK,
+					 uval);
+		break;
+	case MAX31827_DEBUGFS_ALARM_POLARITY:
+		uval = FIELD_PREP(MAX31827_CONFIGURATION_ALRM_POL_MASK, uval);
+		ret = regmap_update_bits(st->regmap,
+					 MAX31827_CONFIGURATION_REG,
+					 MAX31827_CONFIGURATION_ALRM_POL_MASK,
+					 uval);
+		break;
+	case MAX31827_DEBUGFS_COMP_INT:
+		uval = FIELD_PREP(MAX31827_CONFIGURATION_COMP_INT_MASK, uval);
+		ret = regmap_update_bits(st->regmap,
+					 MAX31827_CONFIGURATION_REG,
+					 MAX31827_CONFIGURATION_COMP_INT_MASK,
+					 uval);
+		break;
+	case MAX31827_DEBUGFS_FAULT_QUEUE:
+		uval = FIELD_PREP(MAX31827_CONFIGURATION_FLT_Q_MASK, uval);
+		ret = regmap_update_bits(st->regmap,
+					 MAX31827_CONFIGURATION_REG,
+					 MAX31827_CONFIGURATION_FLT_Q_MASK,
+					 uval);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static const struct file_operations max31827_fops = {
+	.read = max31827_debugfs_read,
+	.write = max31827_debugfs_write,
+};
+
+static void max31827_debugfs_remove(void *dir)
+{
+	debugfs_remove_recursive(dir);
+}
+
+static int max31827_init_debugfs(struct max31827_state *st,
+				 struct i2c_client *client)
+{
+	struct dentry *debugfs;
+	int ret, i;
+
+	debugfs = debugfs_create_dir(client->name, NULL);
+	if (!debugfs)
+		return -ENOENT;
+
+	for (i = 0; i < MAX31827_DEBUGFS_NUM_ENTRIES; ++i)
+		st->psu.debugfs_entries[i] = i;
+
+	ret = devm_add_action_or_reset(&client->dev, max31827_debugfs_remove,
+				       debugfs);
+	if (ret)
+		return ret;
+
+	debugfs_create_file("timeout", 0644, debugfs,
+			    &st->psu.debugfs_entries[MAX31827_DEBUGFS_TIMEOUT],
+			    &max31827_fops);
+	debugfs_create_file("resolution", 0644, debugfs,
+			    &st->psu.debugfs_entries[MAX31827_DEBUGFS_RESOLUTION],
+			    &max31827_fops);
+	debugfs_create_file("alarm_polarity", 0644, debugfs,
+			    &st->psu.debugfs_entries[MAX31827_DEBUGFS_ALARM_POLARITY],
+			    &max31827_fops);
+	debugfs_create_file("comp_int", 0644, debugfs,
+			    &st->psu.debugfs_entries[MAX31827_DEBUGFS_COMP_INT],
+			    &max31827_fops);
+	debugfs_create_file("fault_queue", 0644, debugfs,
+			    &st->psu.debugfs_entries[MAX31827_DEBUGFS_FAULT_QUEUE],
+			    &max31827_fops);
+	debugfs_create_file("pec_error", 0444, debugfs,
+			    &st->psu.debugfs_entries[MAX31827_DEBUGFS_PEC_ERROR],
+			    &max31827_fops);
+
+	return 0;
+}
+#else
+static int max31827_init_debugfs(struct max31827_state *st,
+				 struct i2c_client *client)
+{
+	return 0;
+}
+#endif /* CONFIG_DEBUG_FS */
+
 static int max31827_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
@@ -698,7 +890,13 @@ static int max31827_probe(struct i2c_client *client)
 							 &max31827_chip_info,
 							 max31827_groups);
 
-	return PTR_ERR_OR_ZERO(hwmon_dev);
+	if (IS_ERR(hwmon_dev))
+		return dev_err_probe(dev, PTR_ERR(hwmon_dev),
+				     "Failed to register device");
+
+	max31827_init_debugfs(st, client);
+
+	return 0;
 }
 
 static const struct of_device_id max31827_of_match[] = {
-- 
2.34.1

Re: [PATCH 2/2] drivers: hwmon: max31827: Add debugfs support

[Nuno Sá]

On Wed, 2024-05-22 at 15:39 +0300, Radu Sabau wrote:
> Add debugfs support by creating directory in sys-fs which includes
> debugfs specific files used for configuring the device by
> preference.
> 
> Signed-off-b: Radu Sabau <radu.sabau@analog.com>
> ---
>  Documentation/hwmon/max31827.rst |  25 ++++
>  drivers/hwmon/max31827.c         | 202 ++++++++++++++++++++++++++++++-
>  2 files changed, 225 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
> index 9c11a9518c67..940310be6075 100644
> --- a/Documentation/hwmon/max31827.rst
> +++ b/Documentation/hwmon/max31827.rst
> @@ -142,3 +142,28 @@ usage (+33% for both write and reads) in normal conditions.
>  Since this operation implies there will be an extra delay to each
>  transaction, PEC can be disabled or enabled through sysfs.
>  Just write 1  to the "pec" file for enabling PEC and 0 for disabling it.
> +
> +DebugFs entries
> +---------------
> +
> +The chip also has a configuration register where each bit stands for a specific
> +functionality to be configured. Hence as one would like to have access to these
> +features, we give access to them in debugfs.
> +
> +.. warning:: The debugfs interface is subject to change without notice
> +             and is only available when the kernel is compiled with
> +             ``CONFIG_DEBUG_FS`` defined.
> +
> +``/sys/kernel/debug/max31827/``
> +contains the following attributes:
> +
> +==============  ===============================================================
> +alarm_polarity  Write 1 for ALARM pin active state is low, 0 otherwise
> +comp_int        Set to 1 if OT and UT status bits are in interrupt mode
> +fault_queue     Number of consecutive temperature faults until OT and UT faults
> +                are indicated in status bits
> +pec_error       Set to 1 if PEC Enable bit is set, 0 otherwise
> +resolution      2-bit value that select the conversion resolution, please see
> +                datasheet for corresponding values
> +timeout         Write 1 do disable bus timeout, 0 otherwise

From the description, the above really don't look like they belong into a debug
interface...

- Nuno Sá
> 

Re: [PATCH 2/2] drivers: hwmon: max31827: Add debugfs support

[Guenter Roeck]

On 5/22/24 06:10, Nuno Sá wrote:
> On Wed, 2024-05-22 at 15:39 +0300, Radu Sabau wrote:
>> Add debugfs support by creating directory in sys-fs which includes
>> debugfs specific files used for configuring the device by
>> preference.
>>
>> Signed-off-b: Radu Sabau <radu.sabau@analog.com>
>> ---
>>   Documentation/hwmon/max31827.rst |  25 ++++
>>   drivers/hwmon/max31827.c         | 202 ++++++++++++++++++++++++++++++-
>>   2 files changed, 225 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
>> index 9c11a9518c67..940310be6075 100644
>> --- a/Documentation/hwmon/max31827.rst
>> +++ b/Documentation/hwmon/max31827.rst
>> @@ -142,3 +142,28 @@ usage (+33% for both write and reads) in normal conditions.
>>   Since this operation implies there will be an extra delay to each
>>   transaction, PEC can be disabled or enabled through sysfs.
>>   Just write 1  to the "pec" file for enabling PEC and 0 for disabling it.
>> +
>> +DebugFs entries
>> +---------------
>> +
>> +The chip also has a configuration register where each bit stands for a specific
>> +functionality to be configured. Hence as one would like to have access to these
>> +features, we give access to them in debugfs.
>> +
>> +.. warning:: The debugfs interface is subject to change without notice
>> +             and is only available when the kernel is compiled with
>> +             ``CONFIG_DEBUG_FS`` defined.
>> +
>> +``/sys/kernel/debug/max31827/``
>> +contains the following attributes:
>> +
>> +==============  ===============================================================
>> +alarm_polarity  Write 1 for ALARM pin active state is low, 0 otherwise
>> +comp_int        Set to 1 if OT and UT status bits are in interrupt mode
>> +fault_queue     Number of consecutive temperature faults until OT and UT faults
>> +                are indicated in status bits
>> +pec_error       Set to 1 if PEC Enable bit is set, 0 otherwise
>> +resolution      2-bit value that select the conversion resolution, please see
>> +                datasheet for corresponding values
>> +timeout         Write 1 do disable bus timeout, 0 otherwise
> 
>>From the description, the above really don't look like they belong into a debug
> interface...
> 

Correct. The chip should be configured using firmware properties, which for the
most part is already supported. An acceptable exception is PEC, but that
configuration flag, if implemented as attribute, should be attached to the
i2c client interface to match other drivers.

Guenter